Do these caps fit standard tire valve stems?

Yes. These are universal valve caps designed to fit any standard metal or rubber tire valve stem. Just screw them on like standard caps.

Will 45mm height interfere with my wheels or suspension?

Unlikely on most modern wheels. The 45mm height is still compact, but if you're running aggressive fitment or custom suspension, test-fit before committing. No clearance data covers every setup.

Can these be painted or refinished if the blue doesn't match my build?

The anodized finish is durable but not designed for over-painting. If you need a different color, powder coating is possible — anodize will need to be stripped first. Plan on sending them to a local coater.